fixed typo in transform_iterator documentation resolves issue #136
fixed typo in transform_iterator documentation
resolves issue #136

Reported by David Coerjolly

rdmenezes/thrust,julianromera/thrust,Vishwa07/thrust,lishi0927/thrust,rdmenezes/thrust,bfurtaw/thrust,h1arshad/thrust,allendaicool/thrust,h1arshad/thrust,lishi0927/thrust,Vishwa07/thrust,bfurtaw/thrust,UIKit0/thrust,h1arshad/thrust,hemmingway/thrust,levendlee/thrust,bfurtaw/thrust,h1arshad/thrust,google-code-export/thrust,malenie/thrust,google-code-export/thrust,julianromera/thrust,lishi0927/thrust,malenie/thrust,bfurtaw/thrust,lishi0927/thrust,Vishwa07/thrust,rdmenezes/thrust,hemmingway/thrust,allendaicool/thrust,malenie/thrust,levendlee/thrust,Vishwa07/thrust,allendaicool/thrust,levendlee/thrust,google-code-export/thrust,rdmenezes/thrust,UIKit0/thrust,malenie/thrust,allendaicool/thrust,hemmingway/thrust,hemmingway/thrust,levendlee/thrust,julianromera/thrust,google-code-export/thrust,julianromera/thrust,UIKit0/thrust,UIKit0/thrust